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My post re the Vncent was deleted but there are all sorts of posts re other bikes that are not Commando (I have owned several Ducks). So what did I do that made folks mad?
Uh...I'm a little confused...
- Thread starter MexicoMike
- Start date
So am I, Mike, but for a different reason. In the thread on the Ducati 450 Desmo rebuild, someone asked wht type valve springs it had. As far as I was aware, "Desmo" is an abbreviation for "desmodromic", a valve actuation system that uses cams to both open and close the valves - no springs.
Did I mis-interpret the question or did Ducati use the name with a little bit of mechanical artistic license? They DID make a true desmodromic engine, a 250 if memory serves, but not very many were made.
Did I mis-interpret the question or did Ducati use the name with a little bit of mechanical artistic license? They DID make a true desmodromic engine, a 250 if memory serves, but not very many were made.
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frankdamp said:
"Desmodromic" valve operation doesn't necessarily mean there are no valve springs whatsoever.
http://www.usq.edu.au/users/grantd/moto ... /DESMO.HTM
MexicoMike said:
Mike, if you'd only asked the question "I wonder how well Norton Commando carbs work on a big Vin ? " then the thread could have stayed where it was !
I've been up close to plenty of Vincents, thrashed down the pub with them as well but they all look the same to me. I dare say that there are Vincent owners who can't tell a 750 Commando from an 850 :roll:
frankdamp said:
Hello Frank, Desmo Ducatis do come from the factory fitted with light valve springs,
The picture LAB has posted a link to is of a Desmo set up in a single, the springs are very strong and could possibly be used to close the valves by themselves without the closing rockers, etc.
As it was early in the sale to the public of Desmo bikes I can only assume that Ducati wasn't going to take a chance with relying on the valve gear shimming to be always done properly and chose to add heavy springs just in case.
If any of the Desmo engined bikes have the springs removed and they are shimmed correctly they will run perfectly.
Some believe that a very light spring can assist the closing valve when the engine is not at operating temp.
graeme
This is a Desmo set up from a 2 valve 500 Pantah. Pretty much the same as most 2 valve V twins.
You can see the small spring which hooks under the closing rocker, then the other end sits on the floor of the head.
Different to the singles springs and shim set up. But can be retrofitted to the singles to save excess load on the bevels and Oldham coupling.
graeme
You can see the small spring which hooks under the closing rocker, then the other end sits on the floor of the head.
Different to the singles springs and shim set up. But can be retrofitted to the singles to save excess load on the bevels and Oldham coupling.
graeme
L.A.B. said:Norton also experimented with desmodromic valve gear on a Manx engine, obviously their system couldn't have been very successful?
Maybe not in a Manx, but didn't Vanwall use it in their Formula One car?? (basically 4 x Manxs to give a 2litre engine) I seem to remember that they used Desmo valve actuation too
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